Occasionally, you'll see code like this (after initial cleanup):

    var_v0_2 = crc & 0x80000000;
    do {
       if (var_v0_2 != 0) {
           crc = (crc << 1) ^ 0x1EDC6F41;
       } else {
           crc <<= 1;
       }
       var_a0 += 1;
       var_v0_2 = crc & 0x80000000;
    } while (var_a0 < 8U);

The thing with var_v0_2 is unnatural. GCC sometimes does these loop rotation tricks, seemingly to save registers (don't ask me how exactly it does). You want to un-rotate back into:

    do {
       var_v0_2 = crc & 0x80000000;
       if (var_v0_2 != 0) {
           crc = (crc << 1) ^ 0x1EDC6F41;
       } else {
           crc <<= 1;
       }
       var_a0 += 1;
    } while (var_a0 < 8U);

and then of course, you can clean up the rest:

for (i = 0; i < 8; ++i) {
    if (crc & 0x80000000) {
        crc = (crc << 1) ^ 0x1EDC6F41;
    } else {
        crc <<= 1;
    }
}

Last one tomorrow, I think.